Method and apparatus of a substrate etching system and process

ABSTRACT

Embodiments of the invention relate to a substrate etching system and process. In one embodiment, a method may include depositing material on the substrate during a deposition process, etching a first layer of the substrate during a first etch process, and etching a second layer of the substrate during a second etch process, wherein a first bias power is applied to the substrate during the first process, and wherein a second bias power is applied to the substrate during the second etch process. In another embodiment, a system may include a gas delivery system containing a first gas panel for supplying a first gas to a chamber, a second gas panel for supplying a second gas to the chamber, and a plurality of flow controllers for directing the gases to the chamber to facilitate rapid gas transitioning between the gases to and from the chamber and the panels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent application Ser. No. 61/038,664, filed Mar. 21, 2008, U.S. provisional patent application Ser. No. 61/040,570, filed Mar. 28, 2008, and U.S. provisional patent application Ser. No. 61/094,820, filed Sep. 5, 2008, the disclosures of which are herein incorporated by reference in their entirety.

BACKGROUND

1. Field

Embodiments of the invention generally relate a substrate processing system and related substrate process, such as an etching/deposition process. In one aspect, the invention relates to an improved silicon etch system. In another aspect, the invention relates to a fast gas exchange system. In a further aspect, the invention relates to providing a dual etch/deposition process. In an even further aspect, the invention relates to providing rapid gas transition processes using a system including a processing chamber and a gas delivery system while processing a substrate in the chamber.

2. Description of the Related Art

The fabrication of microelectronic devices includes a number of different stages, each including a variety of processes. During one stage, a particular process may include imparting a plasma to the surface of a substrate, such as a silicon substrate, to alter the physical and material properties of the substrate. This process may be known as etching, which may involve the removal of materials to form holes, vias, and/or other openings (referred to herein as “trenches”) in the substrate.

Plasma etch reactors are commonly used for etching trenches in semiconductor substrates. These reactors contain a chamber within which the substrate is supported. At least one reactive gas is supplied to the chamber and a radio frequency signal is coupled to the reactive gas to form the plasma. The plasma etches the substrate that is positioned within the reactor. The substrate may also be coupled to a radio frequency signal to bias the substrate during the etching process to enhance etching performance and trench profile.

These trench profiles often require different critical dimensions. The critical dimensions include width, depth, aspect ratio, resist selectivity, roughness of the sidewalls, and planarity of the sidewalls. These critical dimensions may be controlled by various factors, two of which are etching time and etching rate, which further depend on the materials being etched and the type of etching system being used.

One material of particular importance is silicon. Through silicon via (“TSV”) etching is a unique application that requires a low frequency bias and a low temperature environment to form deep trenches in a silicon substrate. However, during fabrication, the silicon is generally covered by multiple layers of other materials, such as an oxide layer and a metal layer that are deposited on the silicon. Oxides and metals include different etching requirements than that of silicon, such as a high frequency bias. In addition, during the deposition step, a thin film polymer layer may be deposited onto the layers of the substrate as the trench is being formed to protect the trench sidewalls prior to the etching step. This polymer layer may further include different etching requirements than the oxide, metal, or silicon layers. These distinct requirements influence and increase the complexity of the type of etching system used.

One type of etching system may include in situ plasma etching. Using this first type of etching system, a trench can be formed by alternating the removal and deposition of material on a substrate in a single reactor with a removing plasma and a deposition plasma. Another type of etching system may include remote plasma etching. Using this second type of etching system, a trench can be formed as in the in situ system, except that the plasmas may be generated in a remote reactor prior to being introduced onto the substrate located in the primary reactor. In addition to the types of etching systems, the process of etching with each system may also vary. Some etching processes employ multi-step approaches, such as a time multiplexed gas modulation (“TMGM”) system or a Bosch system, that includes several recipe steps, such as etch and deposition step, or etch, flash, and deposition steps. The TMGM process etches a material for a period of time and then deposits a protective film upon the previously etched surface to protect the surface, typically the sidewalls of the trench, from further etching. These two steps are repeated as a deeper and deeper trench is formed. The different types of etching systems and processes has particular advantages and disadvantages when forming different trench profiles in different material layers.

One critical dimension of particular importance when forming a trench, the roughness of the sidewalls, may render a microelectronic device defective if not properly controlled. During the etching cycles, material, is being deposited and removed as the trench is formed. In response, a pattern of striations comprising a series of “peaks” and “valleys” may develop along the sidewalls of the trench, a phenomenon known as “scalloping.” Numerous and larger peaks and valleys increase the roughness of the sidewalls of the trenches.

Therefore, there is a need for an improved method and apparatus of an etching system and process for controlling the etching of a substrate and reducing the roughness of the profiles formed therein.

SUMMARY

In one embodiment, a method of etching a substrate in a chamber may include depositing a protective layer on a first layer disposed on a substrate in an etch reactor, etching the protective layer in the etch reactor, wherein a first bias power is applied during etching of the protective layer, etching the first layer in the etch reactor, wherein a second bias power is applied during etching of the first layer, and repeating the deposition and etching processes to form a profile in the substrate.

In one embodiment, a method of etching a substrate in a chamber may include depositing a polymeric film on the substrate during a deposition process, etching the polymeric film deposited on the substrate during a first etch process, and etching the substrate during a second etch process, thereby forming a profile in the substrate, wherein a first bias power is applied to the substrate during the first process, and wherein a second bias power is applied to the substrate during the second etch process.

In one embodiment, a gas delivery system may include a chamber for processing a substrate, a first gas panel in communication with the chamber by a first gas delivery line, wherein the first gas delivery line includes a first plurality of flow controllers, and a second gas panel in communication with the chamber by a second gas delivery line, wherein the second gas delivery line includes a second plurality of flow controllers, wherein the first and second plurality of flow controllers are selectively operable to direct gases from the first and second panels, respectively, to the chamber and to one or more exhausts that are in communication with the first and second gas delivery lines.

In one embodiment, a method of supplying gases to a chamber may include supplying a first gas to the chamber from a first gas panel through a first gas delivery line, directing a second gas to an exhaust from a second gas panel through a second gas delivery line while the first gas is supplied to the chamber, and directing the first gas to the exhaust and supplying the second gas to the chamber, wherein the first gas is removed from the chamber prior to introduction of the second gas into the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 illustrates a substrate etching system according to one embodiment of the invention.

FIG. 2 illustrates a fast gas exchange system according to one embodiment of the invention.

FIG. 3 illustrates another fast gas exchange system according to one embodiment of the invention.

FIGS. 4A-B illustrate a profile etched into a substrate.

FIG. 5A illustrates a prior art etching cycle.

FIG. 5B illustrates an etching cycle according to one embodiment of the invention.

FIG. 6A illustrates a trench profile formed using a prior art method.

FIG. 6B illustrates a trench profile formed using a method according to one embodiment of the invention.

FIGS. 7A-C illustrate a gas transition process according to one embodiment of the invention.

FIGS. 8A-C illustrate another gas transition process according to one embodiment of the invention.

FIGS. 9A-D illustrate another gas transition process according to one embodiment of the invention.

FIG. 10 illustrates a gas delivery system according to one embodiment of the invention.

DETAILED DESCRIPTION

The invention generally relates to an apparatus and method of a substrate etching system and process. As set forth herein, the invention will be described as it relates to a silicon etching system and process. It is to be noted, however, that aspects of the invention are not limited to use with silicon etching, but are applicable to etching other types of materials. To better understand the novelty of the apparatus of the invention and the methods of use thereof, reference is hereafter made to the accompanying drawings.

A method and apparatus for etching a profile, such as a deep trench, in a silicon substrate having oxide and metal layers disposed on the substrate, wherein the etching cycle comprises a plurality of plasma processes that are performed in situ within a single, fully automated, reactor is provided. Each such etching cycle comprises a deposition step, a first etch step, and a second etch step. Each of the steps is an individual plasma process that is defined by a composition of a gaseous mixture supplied into the chamber of the reactor where the substrate is supported. Different compositions of gaseous mixtures may be supplied to the chamber during each individual step. The reactor generally comprises a source of power for generating and maintaining a plasma (referred to herein as “source power”) and a source of power for biasing a substrate (referred to herein as “bias power”), each independently controlled.

The bias power may be pulsed, e.g. repeatedly releasing energy, while the source power may be continuously applied. In particular, the bias power may be pulsed using generator pulsing capability set by a control system to provide a percentage of time that the power is on, which is referred to as the “duty cycle.” In one embodiment, the time on and the time off of a pulsed bias power may be uniform throughout the etching cycles. For example, if the power is on for about 3 msec and off for about 15 msec, then the duty cycle would be about 16.67%. The pulsing frequency in cycles per second or hertz (Hz) is equal to 1.0 divided by the sum of the on and off time periods in seconds. For example, when the bias power is on for about 3 msec and off for about 15 msec, for a total of about 18 msec, then the pulsing frequency in cycles per second is about 55.55 Hz. In one embodiment, a specialized pulsing profile where the on/off timing changes during the etching cycles may be used. In one embodiment, by changing the bias power applied to the substrate, the etching cycle may switch between the deposition and/or etching steps. The bias power is pulsed to help reduce scalloping of the trench sidewalls, improve resist selectivity, improve the etch rate, and prevent material interface undercut.

FIG. 1 illustrates a sectional view of a system, such as a reactor 100, for processing a variety of substrates and accommodating a variety of substrate sizes.

In one embodiment, the reactor 100 may include the source power 15 and a matching network 17, the bias power 20 and a matching network 21, a chamber 25, a pump 30, a valve 35, a ceramic electrostatic chuck 40, a chiller 45, a lid 50, a gas nozzle 55, and a gas delivery system 102. In one embodiment, the gas delivery system 102 is located in a housing 105 disposed directly adjacent, such as under, the chamber 25. The gas delivery system 102 selectively couples one or more gas sources located in one or more gas panels 104 to the gas nozzle 55 to provide process gases to the chamber 25. The housing 105 is located in close proximity to the chamber 25 to reduce gas transition time when changing gases, minimize gas usage, and minimize gas waste. The reactor 100 may further include a lift 27 for raising and lowering the chuck 40 that supports a substrate in the chamber 25. The chamber 25 further includes a body having a lower liner 22, an upper liner 23, and a door 24. The valve 35 may be disposed between the pump 30 and the chamber 25 and may be operable to control pressure within the chamber 25. The ceramic electrostatic chuck 40 may be disposed within the chamber 25. The lid 50 may be disposed on the chamber 25. The gas nozzle 55 may comprise a tunable gas nozzle having one or more outlets to selectively direct gas flow from the gas delivery system 102 to the chamber 25. The gas nozzle 55 may be operable to direct gas flow into different areas within the chamber 25, such as the center area and/or the side areas of the chamber 25. In one embodiment, the gas nozzle 55 may include a first outlet that introduces gases from the top of the chamber 25 and a second outlet that introduces gases from the side of the chamber 25 to selectively control the distribution of the gases in the chamber 25. The gas delivery system 102 may be used to supply at least two different gas mixtures to the chamber 25 at an instantaneous rate as further described below. In an optional embodiment, the reactor 100 may include a spectral monitor operable to measure the depth of an etched trench and a deposited film thickness as the trench is being formed in the chamber 25, with the ability to use other spectral features to determine the state of the reactor. The reactor 100 may be configured to accommodate a variety of substrate sizes, for example a substrate diameter of up to about 300 mm. In operation, and as will be discussed herein, the reactor 100 is configurable to produce etched substrate trench sidewall profiles having angles that taper in a range of about 85 degrees to about 92 degrees, and etched substrate trenches having depths that range from about 10 micrometers to about 500 micrometers.

In one embodiment, the reactor 100 may be coupled to a system that includes a metal etch reactor and optionally a post metal etch passivation chamber.

In one embodiment, the source power 15 for generating and maintaining the plasma processes is coupled to the chamber 25 via a power generating apparatus enclosed in a housing 11 disposed above the chamber 25. The source power 15 may be operable to generate a radio frequency within a range from about 12 MHz to about 13.5 MHz, having pulsing capabilities, a power within a range from about 10 watts to about 5000 watts, and may further include a dynamic matching network 17. In one example, the source power 15 may be operable to generate a 13 MHz radio frequency having pulsing capabilities. The source power 15 may comprise a dual tunable source so that the radio frequency may be changed during an etching cycle. In one embodiment, the source power 15 may comprise a remote plasma source capable of generating high levels of plasma disassociation that is mountable to the reactor 100. When using a remote plasma source, the reactor 100 may further include a plasma distribution plate or series of plates disposed in the chamber 25 to help distribute the plasma to the substrate. In one embodiment, the reactor 100 may include both an in-situ source power and a remote plasma source power, wherein the plasma is generated in a remote plasma chamber using the remote plasma source power and transferred to the reactor chamber 25, wherein the in-situ source power 15 maintains the generated plasma within the chamber 25. In one embodiment, an etching cycle may be performed wherein the power range, i.e. the wattage of the power source 15, may be increased or decreased during the etching cycle. The source power 15 may be pulsed during the etching cycle.

In one embodiment, the bias power 20 for biasing the substrate is coupled to the chamber 25 and the chuck 40. The bias power 20 may be operable to generate a radio frequency of about 2 MHz having pulsing capabilities, a low power range from about 10 watts to about 500 watts, and may further include a dynamic matching network 21. In one embodiment, the bias power 20 may be capable of generating a selectable radio frequency range from about 400 kHz to about 2 MHz, from about 100 kHz to about 2 MHz, and from about 100 kHz to about 13.56 MHz, having pulsing capabilities, a low power range from about 10 watts to about 500 watts, and may further include a dynamic matching network or a fixed matching network and a frequency tuner. In one embodiment, an etching cycle may be performed wherein the power range, i.e. the wattage of the bias power 20, may be increased or decreased during the etching cycle. In one embodiment, an etching cycle may include a deposition step, a first etch step, and a second etch step, wherein the bias power 20 is used during the first etch step and the bias power 20 is decreased or increased during the second etch step. For example, the radio frequency of the bias power may be decreased or increased from the first etch step to the second etch step.

The bias power 20 may be pulsed during the etching cycle. To pulse the bias power 20, the radio frequency power is switched on and off during the etching cycle. The pulsing frequency of the bias power 20 may range from about 10 Hz to about 1000 Hz, and may range from about 50 Hz to about 180 Hz. In one embodiment, the switching of the power on and off is uniformly distributed in time throughout the etching cycle. In one embodiment, the timing profile of the pulsing may be varied throughout the etching cycle, and may depend on the composition of the substrate. The percentage of time the bias power 20 is switched on, i.e. the duty cycle as described above, is directly related to the pulsing frequency. In one embodiment, when the pulsing frequency ranges from about 10 Hz to about 1000 Hz, the duty cycle ranges from about 2% to about 40%. In one embodiment, when the pulsing frequency ranges from about 50 Hz to about 180 Hz, the duty cycle ranges from about 5% to about 30%. The bias power frequency and the pulsing frequency may be adjusted depending on the substrate material being processed.

In one embodiment, the chiller 45 may be operable to control the temperature within the chamber 25 and of the substrate located within the chamber 25. The chiller 45 may be located near and coupled to chamber 25. The chiller 45 may include a low temperature chiller, such as a sub-zero point of use thermoelectric chiller, and may further include a direct cooling mechanism for ultra lower temperatures. The chiller 45 is operable to generate temperatures in the range of about −20 degrees to about 80 degrees Celsius, located near the chamber 25 to achieve a faster reaction time, and may include ramping capabilities to allow some level of control to help improve the etch rate. In one embodiment, the chiller 45 is capable of generating temperatures in the range of about −10 degrees to about 60 degrees Celsius and may be located near the chamber 25 to achieve a faster reaction time. In one embodiment, the chiller 45 may be operable to lower the temperature from about −10 degrees Celsius to about −20 degrees Celsius in the chamber 25.

In one embodiment, the reactor 100 is operable to maintain a chamber pressure range of about 10 mTorr to about 1000 mTorr with the pump 30 and the valve 35, which is coupled to the chamber 25. The chamber pressure can be adjusted during the etching cycle to further improve the trench profiles. For example, the chamber pressure may be rapidly decreased or increased when switching from the deposition step to the etch step. The pump 30 may comprise a turbo pump, a 2600 L/s turbo pump for example, operable to process flows in the range of about 100 sccm to about 1000 sccm throughout the chamber 25. In conjunction with the pump 30, the valve 35 may comprise a throttling gate valve with a fast reaction time to help control the process flow and the pressure changes. The reactor 100 may further include a dual manometer to measure the pressure in the chamber 25. In one embodiment, the reactor 100 is operable to maintain a dynamic pressure in the range of about 10 mTorr to about 250 mTorr during the etching cycle. Optionally, an automatic throttling gate valve control or a valve with preset control points may be utilized, and the dynamic pressure may be sustained at a set-point while changing flow parameters.

FIG. 2 depicts a schematic diagram of one embodiment of the gas delivery system 102 having a fast gas exchange 200. The fast gas exchange 200 includes a housing 205 (such as the housing 105 described above) that contains a first flow controller 240, a second flow controller 230, numerous optional flow restrictors 260 and valves 250 to selectively direct gases into the chamber 25 (shown in FIG. 1) via outlets 270 and 280, and an exhaust 290 for dumping the gas into the chamber exhaust downstream of the pump 30. Specifically, four flow restrictors 260 and eight valves 250 are shown in FIG. 2, but the number of flow restrictors 260 and valves 250 may vary if used. The first flow controller 240 is in communication with the outlet 270 via flow line 272, which is in communication with outlet flow line 273. The second flow controller 230 is in communication with the outlet 270 via flow line 271, which is also in communication with outlet flow line 273. Each of the first and second flow controllers are in communication with the exhaust 290 via flow lines 272 and 271, respectively, which are each individually coupled to exhaust flow line 291. The first flow controller 240 is also separately in communication with the outlet 280 via flow line 282, which is in communication with outlet flow line 283. The second flow controller 230 is also separately in communication with the outlet 280 via flow line 281, which is also in communication with outlet flow line 283. Each of the first and second flow controllers are in communication with the exhaust 290 via flow lines 282 and 281, respectively, which are each individually coupled to exhaust flow line 291. One or more of the flow paths from the first and second flow controllers to the exhaust 290, via flow lines 271, 272, 281, 282, and 291 may each define a pre-flow gas path as further described below. The one or more optional flow restrictors 260 and valves 250 may be located between the first and second flow controllers 240 and 230 and the outlets 270 and 280 and the exhaust 290 to control delivery of process gases to the outlets 270 and 280 and the exhaust 290. The outlets 270 and 280 may be in communication with the one or more outlets of the gas nozzle 55 (described above) to selectively control the distribution of gases into the chamber 25. The fast gas exchange 200 and in particular the first and second flow controllers 240 and 230 are coupled to a first gas panel 220 and a second gas panel 210, respectively, for supplying process gases to the chamber 25 using the fast gas exchange 200. The first and second gas panels 210 and 220 may be coupled to the fast gas exchange 200 via a first flow line 217 and a second flow line 227. The first and second gas panels may each include one or more gas sources 215 and 225 and are operable to supply one or more gases through the first and second flow lines 217 and 227 to the fast gas exchange 200 and thus the chamber 25. When configured for silicon etching, the fast gas exchange 200 supplies a first gas, such as sulfur hexafluoride (SF₆), to the chamber 25 during the first etch step and the second etch step from the first gas panel 210, and also supplies a second gas, such as perfluorocyclobutane (C₄F₈), to the chamber 25 during the deposition step from the second gas panel 220. In one example, the first gas panel 210 and the second gas panel 220 are operable to deliver SF₆ and C₄F₈ at about 1000 sccm, helium at about 500 sccm, and oxygen (O₂) and argon at about 200 sccm. In one embodiment, a third gas panel having a plasma sustaining gas, such as argon, may be coupled to the fast gas exchange 200 and operable to continuously supply the gas to the chamber 25 during the etching and deposition steps.

In operation, as the gas from the first gas panel 210 is supplied to the chamber 25, the first flow controller 240 may direct the gas to the outlet 280 via flow line 282, the outlet 270 via flow line 272, or both outlets. The optional flow restrictors 260 may be utilized to control the flow of gases within the fast gas exchange 200. As the gas is being supplied to the chamber 25, the valves 250 are operable to open the flow paths to the chamber 25 and close the flow paths to the exhaust flow line 291 and thus the exhaust 290. When the etching cycles switch steps, the gas from the second gas panel 220 may be supplied to the chamber 25 in a similar manner as the first gas panel 210. When the gas from the second gas panel 220 is being supplied to the chamber 25, the valves 250 may be operable to close the flow paths from the first gas panel 210 to the chamber 25 and open the flow paths to the exhaust flow line 291 and thus the exhaust 290 to dump the gas in the flow lines. In one example, gas may be supplied from the first gas panel 210 to the chamber 25 during the deposition steps, and gas may be supplied from the second gas panel 220 to the chamber 25 during the etching steps. Both gas panels 220 and 210 may be used for both deposition and etching steps.

In an alternative embodiment, as shown in FIG. 3, a fast gas exchange may be utilized. The fast gas exchange 300 includes a housing 305 (such as the housing 105 described above) that contains a first flow controller 340, a second flow controller 345, and a third flow controller 347 that are in communication with each other to selectively direct gases into a chamber 310 (such as chamber 25 of the reactor 100 shown in FIG. 1), a first exhaust 360, and/or a second exhaust 370. The fast gas exchange 300 and in particular the first flow controller 340 may be coupled to a first gas panel 320 via flow line 341. In an embodiment, suitable for etching silicon, the first gas panel 320 may include a plurality of gas sources 322, including but not limited to, sulfur hexafluoride, oxygen, argon, trifluoromethane (CHF₃), and/or helium. Each of the flow controllers 340, 345, and 347 may include flow control valves operable to direct the gases to the exhausts 360 and 370 and/or the chamber 310. The flow control valves may include pneumatic actuators for pneumatic operation to allow rapid response and provide numerous flow configurations. In addition, the flow controllers 340, 345, and 347 may be in communication with an operating system to control and monitor the operation of the valves. Flow restrictors 346 and 348 may optionally be coupled to the third flow controller 347 to restrict the flow to the second exhaust 370 and/or the chamber 310.

In one embodiment, the first flow controller 340 may be configured to direct gas to the first exhaust 360 via flow line 343 (thereby defining a fast evacuation path further described below) and/or the second flow controller 345 via flow line 342. The second flow controller 345 may be configured to direct gas to the chamber 310 via flow line 325 and/or the third flow controller 347 via flow line 344. The third flow controller 347 may be configured to direct gas to the second exhaust 370 through the optional flow restrictor 348 via flow line 349 (thereby defining a pre-flow gas path further described below) and/or the chamber 310 through the optional flow restrictor 346 via flow line 321, which may be in communication with flow line 325.

The fast gas exchange 300 may also include a first flow controller 350, a second flow controller 355, and a third flow controller 357 disposed within the housing 305 and in communication with each other to direct gases into the chamber 310, the first exhaust 360, and/or the second exhaust 370. The fast gas exchange 300 and in particular the first flow controller 350 may be coupled to a second gas panel 330 via flow line 351. In an embodiment, suitable for etching silicon, the second gas panel 330 may include a plurality of gas sources 332, including but not limited to perfluorocyclobutane, oxygen, argon, trifluoromethane, and/or helium. Each of the flow controllers 350, 355, and 357 may include flow control valves operable to direct the gases to the exhausts 360 and 370 and/or the chamber 310. The flow control valves may include pneumatic operation to allow rapid response and provide numerous flow configurations. In addition, the flow controllers 350, 355, and 357 may be in communication with an operating system to control and monitor the operation of the valves. Flow restrictors 356 and 358 may optionally be coupled to the third flow controller 347 to restrict the flow to the second exhaust 370 and/or the chamber 310.

In one embodiment, the first flow controller 350 may be configured to direct gas to the first exhaust 360 via flow line 353 (thereby defining a fast evacuation path further described below) and/or the second flow controller 355 via flow line 352. The second flow controller 355 may be configured to direct gas to the chamber 310 via flow line 335 and/or the third flow controller 357 via flow line 354. The third flow controller 357 may be configured to direct gas to the second exhaust 370 through the optional flow restrictor 358 via flow line 359 (thereby defining a pre-flow gas path further described below) and/or the chamber 310 through the optional flow restrictor 356 via flow line 331, which may be in communication with flow line 335.

In operation, parallel flow lines 325 and 335 are configured to deliver gases independently to the chamber 310 through a series of flow controllers and optional restrictions, such as flow controllers 340, 345, 347 and 350, 355, 357, and optionally flow restrictors 346 and 356 to allow rapid gas switching. The flow lines 325 and 335 are also operable to rapidly deliver gases independent and/or directly into the chamber 310 to eliminate any gas delay observed through the optional flow restrictors 346 and 356. In an alternative embodiment, the flow lines 325 and 335 may tie-in to each other prior to entering the chamber 310. A multitude of gas deliveries and configurations may be provided with the fast gas exchange 300. In one embodiment, a first gas (or combination of gases) may be delivered straight into the chamber 310, such as through flow lines 341, 342, and 325, and a second gas (or combination of gases) may be pulsed through the flow restrictor 356 of flow line 331 via flow lines 354, 352, and 351 to allow controlled delivery options to the chamber 310. Each of the valves in the fast gas exchange 300 may include check valves to prevent back diffusion of the gases delivered through the flow lines. The flow controllers 340 and 350 are operable to direct gases through flow lines 343 and 353, which are in communication with the first exhaust 360. The flow controllers 347 and 357 are operable to direct gases through flow lines 349 and 359, which are in communication with the second exhaust 370.

In one embodiment, the fast gas exchange 300 may include an optional flow line 386 that is in communication with either or both of flow lines 341 and 351. The flow line 386 may include an optional flow controller 384 and/or an optional flow restrictor 382. The flow line 386 may be operable to direct gases to an exhaust 380 to dump the gases from all of the flow lines, thereby defining a fast evacuation path further described below. The exhausts 360, 370, and 380 may comprise vacuum environments into which the gases are directed.

In one embodiment, the fast gas exchange 300 may also be coupled to an optional gas panel 390 to provide a gas source 392, such as a purge gas, to the chamber 310 via a flow line 395 that is in communication with the flow line 335 in combination with the embodiments described herein. The gas panel 390 may be operable as a quick dump valve to remove any residual gas in the chamber 310 before transitioning between processing gas mixtures to prevent comingling of the processing gas mixtures. The gas panel 390 may also provide a rapid direct line to the chamber 310 to provide a gas for processing with the gases from either or both of the first and second gas panels during an etching cycle. The flow line 395 may include a flow controller and/or restrictor to control flow of the gas 390 to the chamber 310. The gas source 392 may be operable to purge any residual gas mixtures remaining in the chamber 310, as well as the flow lines. In one embodiment, one or more of the flow controllers may be actuated into open positions to purge the residual gas mixtures to one or more of the exhausts 360, 370, and 380 through either or both flow lines 325 and 335 using the gas source 392 supplied from the gas panel 390. A similar gas panel arrangement may be provided in communication with the flow line 325.

In one embodiment, a substrate may be located in the chamber 300 for forming a profile in the substrate during a process. The process may include one or more steps, such as etching steps and deposition steps, which may be alternately and continuously repeated in a variety of orders to form the profile. A first gas mixture including one or more gases provided from the gas sources 322 of the first gas panel 320 may be supplied from the first gas panel 320 to the chamber 310 through the first and second flow controllers 340 and 345 via flow lines 341, 342, and 325 and/or through the first, second, and third flow controllers 340, 345, and 347 via flow lines 341, 342, 344, 321, and 325 during one or more of the process steps. A second gas mixture including one or more gases provided from the gas sources 332 of the second gas panel 330 may be supplied from the second gas panel 330 to the chamber 310 through the first and second flow controllers 350 and 355 via flow lines 351, 352, and 335 and/or through the first, second, and third flow controllers 350, 355, and 357 via flow lines 351, 352, 354, 321, and 335 during one or more of the process steps. The first and second gas mixtures may be rapidly switched and supplied to the chamber 310 when switching process steps. The first and second gas mixtures may also be directed from the respective flow lines 325 and 335 to the exhausts 360, 370, and 380 when switching process steps and while the other gas mixture is being supplied to the chamber 310. In addition, the composition of the gas mixtures may be changed during the switching process steps to provide a different gas mixture to the chamber during a process step. The first and second gas mixtures may also be supplied to the chamber 310 simultaneously during a process step. The flow controllers may provide unrestricted flow paths to the chamber 310.

In one embodiment, the fast gas exchange systems are operable to provide continuous rapid switching of gas mixtures in a chamber while processing a substrate in the chamber when switching from a first etch step to a second etch step and/or to a deposition step using one or more valves, such as a combination of flow controllers, such as three-way valves, which may include pneumatic actuators to provide rapid response actuation. For example, during a deposition step, a first gas mixture may be supplied to the chamber, while a second gas mixture may be routed to the chamber in preparation for introduction into the chamber during an etch step that will follow the deposition step. Each step may last less that 1 second in duration. For example, the deposition step may last about 0.5 seconds and the etch step may last about 0.75 seconds, and the steps may continuously and alternately be repeated to process a substrate in the chamber as the respective gas mixtures are supplied during the representative step. One or more sensors may be attached to the valves to monitor the performance of the gas mixtures supplied to the chamber.

As shown in FIG. 4A, as a trench 400 is etched in one or more layers 410, 420, and 430 of a substrate, a number of scallops 415 may develop along the sidewalls of the trench. The scallops 415 may appear as a series of peaks 411 and valleys 412 along the sidewalls. The scallop measurement 413 may include the depth of the valleys 412, i.e. measuring from the center of the base of the valleys 412 as shown in FIG. 4B. In one embodiment, the length of the valleys 412, i.e. the perpendicular distance from the tip of one peak to the tip of the adjacent peak, and the number of peaks 411 and valleys 412 may be increased or decreased by utilizing the fast gas exchange 200 or 300 with the reactor 100. As the scallop measurement 413 increases, the roughness of the sidewalls may increase. According to one example, utilizing the fast gas exchange 200 or 300, a trench may be formed at an etch rate of about 10 micrometers per minute with the scallop measurement 413 at about 0.1 micrometers. The scallop measurement 413 may be maintained within a reasonable tolerance along the sidewalls as the trench is formed through the entire substrate, for example, the scallop measurement 413 may be greater than or equal to about 0.1 micrometers at the top of the trench and less than or equal to about 0.025 micrometers at the bottom of the trench. In one embodiment, a trench may be formed at an etch rate of about 20 micrometers per minute with the scallop measurement 413 at about 0.1 micrometers. In one embodiment, a trench may be formed at an etch rate of about 10 micrometers per minute with a deposition step that may last a time period within a range from about 1 second to about 2 seconds, and an etch step that may last a time period within a range from about 2 seconds to about 4 seconds. The etch step may include a first etch step and a second etch step.

Utilizing the fast gas exchange 200 or 300, the amount of photo resist remaining on the trench profile after etching may be increased. Also, the fast gas exchange 200 or 300 may improve the resist selectivity as deeper trench profiles are formed.

The fast gas exchange 200 or 300 provides enhanced etching performance. The fast gas exchange 200 or 300 provides the following benefits: reduce gas delay from a mass flow controller to the chamber, eliminate multiple gas species mixing, reduce gas switching time, reduce gas delivery lag between process steps, allow for gas species overlap, allow for multiple zone gas delivery, and allow for remote or local gas panel location. These benefits result in higher overall etch rates, reduced roughness of trench sidewalls, and increased ability to control trench profiles. The fast gas exchange 200 or 300 may be utilized with etching systems that employ multi-step processes, such as the TMGM system or the Bosch system.

In one embodiment, a method of etching a substrate in a chamber includes supplying a first gas from a first gas panel into the chamber during a deposition step, supplying a second gas from a second gas panel into the chamber during a first etch step and a second etch step, and biasing the substrate with a first bias power during the first etch step and a second bias power during the second etch step, wherein the first bias power is greater than the second bias power.

In one embodiment, a method for etching a substrate, such as a silicon substrate, optionally having multiple layers, such as an oxide, a metal, and/or a deposited protective polymeric film, wherein the protective polymeric film contains at least one polymer, co-polymer, oligomer, derivates thereof or combinations thereof, such as a hardmask or a resist mask, disposed on the substrate is provided. The method includes an etching cycle having a deposition step, a first etch step, and a second etch step. The process may include employing a high bias power and a low pressure during the first etch step and employing a low bias power and a higher pressure during the second etch step; the high bias power being used to etch the multiple layers, such as the oxide, metal, and/or polymeric film, and the low bias power being used to etch the substrate, such as the silicon substrate, to form trenches in the substrate. This process results in improved resist selectivity and a reduced roughness of the trench sidewalls.

According to one example, under a conventional silicon etch system, the etch step takes about 40% of its time in removing surface polymers prior to breaking through and etching the silicon isotropically. Bias power is necessary to breakthrough the polymer layer, but the silicon etch is exothermic and consequently requires no bias power. A deposition step of about 5 seconds may be utilized with an etch step of about 10 seconds to provide the best critical dimensions and etch rate. If the bias power is on for the entire 10 seconds of the etch step and the polymer surface is etched after about 4 seconds, then etching the silicon for the about remaining 6 seconds with the bias power reduces resist selectivity and increases roughness of the trench sidewalls. Under this same example, embodiments of the invention address these issues by splitting the etch step into a first etch step that includes a low pressure/high bias power for about 4 seconds, followed by a second etch step that includes a higher pressure/low bias power for the about remaining 6 seconds, resulting in an increase in resist selectivity. In one embodiment, the time of the deposition step may range from about 1 second to about 20 seconds and the time of the etch step may be within a range from about 2 seconds to about 30 seconds.

FIG. 5A illustrates a prior art etching cycle 500 that includes a deposition step 510 lasting about 5 seconds and an etch step 530 lasting about 10 seconds and having an overlap 520 of the steps when switching between steps to etch a silicon substrate. FIG. 5B illustrates an etching cycle 550 performed on the same substrate as the prior art cycle 500, according to one embodiment of the invention. FIG. 5B illustrates a method of etching a silicon substrate that includes depositing a thin film polymeric layer for about 3 seconds during a deposition step 560, etching the polymeric layer for about 3 seconds during a first etch step 570, and etching a silicon layer for about 5 seconds during a second etch step 580, wherein a first bias frequency is applied to the silicon substrate during the first step, wherein a second bias frequency is applied to the silicon substrate during the second etch step, wherein the second bias frequency is less than the first bias frequency. As shown, the etching cycle 550 is about four seconds faster than the prior art etching cycle 500 and may form a substantially similar trench profile. Using the fast gas exchange 200 or 300 may also eliminate any gas overlap when switching from the deposition step to the etching step.

In one embodiment, a method includes increasing resist selectivity by using bias power during the first etch step and zero bias power during the second etch step of an etching cycle.

In one embodiment, a method includes etching metal and oxide layers with about a 2 MHz frequency bias power during a first etch step and then switching to about a 400 kHz frequency bias power during a second etch step to etch a silicon layer. The method may further include a multiple frequency bias power match.

FIG. 6A illustrates an etched feature or profile, such as a trench profile 600 formed using a prior art method. FIG. 6B illustrates a trench profile 650 formed using a method according to one embodiment of the invention. As shown, the trench profile 600 formed using the prior art method has a higher degree of roughness along the sidewalls, e.g. a scallop measurement of greater than about 2 micrometers at an etch rate of about 6.7 micrometers per minute. The trench profile 650 formed using the fast gas exchange 200 or 300 and the reactor 100 reduces the sidewall roughness and produces a smoother profile, e.g. a scallop measurement of less than about 1.5 micrometers at an etch rate of about 5.8 micrometers per minute. The trench profile 650 may also include a smooth and rounded etch-front. Additionally, the two step etch process may be utilized to further achieve a reduced scallop measurement.

In one embodiment, the etching cycle may further include a removal process that includes the removal of a photoresist mask or protective polymeric films remaining on the etched material surface and/or along the trench surfaces. According to one example, the removal process may be completed using an oxygen-containing plasma for a silicon based substrate. This removal process may be conducted after the trench profile is etched using embodiments of the invention.

In one embodiment, the etching cycle may further include an additional etching or removal process, otherwise stated as a sidewall smoothing process, which includes the further smoothing of the etch-generated surface roughness, e.g. scalloping, along the trench profiles. The sidewall smoothing process may be conducted after the removal process discussed above. The sidewall smoothing process may further reduce the depth of the scallops formed on the sidewall surfaces of the etched trenches using a reactive plasma milling process. An exemplary embodiment of a removal process and a reactive plasma milling process is disclosed in pending U.S. patent application Ser. No. ______, filed Aug. 27, 2008, entitled Post Etch Reactive Plasma Milling to Smooth Through Substrate Via Sidewalls and Other Deeply Etched Features, which is incorporated herein by reference in its entirety.

In one embodiment, a reactive plasma milling process is used to subject the scalloped surface of the trench profile to a reactive plasma created from a plasma source gas that includes a reagent, including but not limited to SF₆, NF₃, CF₄, CHF₃, ClF₃, BrF₃, IF₃, or derivatives thereof, which reacts with the material at the surface of the trench profile. The plasma source gas may include an inert gas, which does not react with the trench profile, but works as an impacting force which can impact the trench profile, breaking down and removing material from the scalloping. In one embodiment, after removing residual polymeric materials from a trench profile of a substrate, the trench profile may be treated with a reactive plasma generated from a source gas while the substrate is biased with a bias power. The bias power may be pulsed, i.e. the RF power may be switched on and off while the substrate is being treated. The reactive plasma milling process may be configurable by adjusting process variables such as the composition of the plasma source gas, the temperature of the substrate, the pressure in the process chamber, and the radio frequency power with respect to the bias power and/or the source power, using embodiments of the invention discussed herein.

In one embodiment, a pre-flow gas path may be provided to a chamber, such as the chamber 25 of the reactor 100, using a gas delivery system, such as the fast gas exchange systems 200 and 300. The pre-flow gas path may be a connection from a gas delivery source through a valve to a vacuum environment that is separate from the chamber. Before a gas is requested in the chamber, the gas can flow through the pre-flow gas path allowing flow stabilization before the gas is requested. Additionally any flow controlling devices, such as flow controllers, can have their outputs routed to the pre-flow gas path so that the division of gas flow can be stabilized before the gas flow is delivered to the chamber.

In one embodiment, a fast evacuation path may be provided from a chamber, such as the chamber 25 of the reactor 100, to an exhaust or dump using a gas delivery system, such as the fast gas exchange systems 200 and 300. The fast evacuation path may be a connection from a gas delivery source and a chamber delivery path to the chamber through a valve to a vacuum environment that is separate from the chamber. One or more valves may be used for each chamber delivery path connection as the fast evacuation path can be connected at multiple locations such that there is at least one connection between any two flow controlling devices and/or restrictions. When it is required that the gas in the chamber should change, the valves to the vacuum environment may be opened removing excess gas from the chamber delivery path(s).

In one embodiment, a control of gas flow through a gas delivery system, such as the fast gas exchange systems 200 and 300, over time so that the actual gas flow into a chamber, such as the chamber 25 of the reactor 100, reaches a desired state as quickly as possible is provided. If the chamber delivery path is devoid of gas, the gas delivery system may be operable to increase the flow of each desired gas so that the gas delivery system will reach equilibrium in the shortest possible time. As the flow of gases into the chamber approaches a desired chemical mix and flow rate, the flow of gases through the gas delivery system will be reduced to the desired levels in a manner that maintains desired flow into the chamber. In cases when the gas delivery system will be filled with gases from earlier processes, flows through the gas delivery system may be altered, such as reduced or increased depending on the desired effect, so that the desired flow into the chamber will reach the desired values as quickly as possible. As the gas flow into the chamber approaches the desired chemical mix and flow rate, the flow of the gases will be adjusted toward the desired flow in a manner that maintains the desired flow into the chamber.

In one embodiment, a flow restriction control of the fast evacuation path using a variable restriction, a fixed restriction or a series of selectable fixed restrictions is provided. When the chemical mix delivered to the chamber changes but the flow rate of change needs to be controlled, one or more valves between the chamber delivery path and the fast evacuation path can be throttled to control the rate of evacuation. In some cases the desired chemical mix and flow rate to the chamber can be achieved more quickly by throttling the valves along the chamber delivery path such that some of the gas is evacuated to the fast evacuation path and some of the gas is delivered to the chamber.

In one embodiment, gas delivery to the chamber may continue uninterrupted using residual gas in the chamber delivery path(s) when changing from one chemistry mix and flow rate to another chemistry mix and flow rate. One or more valves can be closed in the chamber delivery path(s) such that gases downstream of the valves will continue to flow into the chamber and gases upstream of the valve may be routed elsewhere. The flow of gases upstream of the closed valves will not reach the chamber while the valves are closed. In this manner, the chamber will run uninterrupted from the gases downstream of the valves (residual gases) while the gases upstream of the valves are changed to the next desired chemical mix and flow rate. Before all of the gases downstream of the valves in the chamber delivery paths are expended into the chamber, the valves will be opened, thereby allowing the next desired chemical mix and flow rate to enter the chamber.

In one embodiment, one or more valves in the chamber delivery paths, the pre-flow paths, and the fast evacuation paths may be sequenced. A timed sequence of the valve actuations may ensure that a desired chemical mix and flow rate are delivered to the chamber at a desired time. Before a new chemical mix and flow rate is required in the chamber, the valves may be actuated to begin the flow of the new chemical mix and flow rate through the chamber delivery paths. At the same time, the valves may be actuated to the chamber delivery paths, the pre-flow paths, and the fast evacuation paths to stabilize flow of the new chemical mix and flow rate through the chamber delivery paths, continue chemical delivery to the chamber from residual gas in the chamber delivery paths, and remove any residual chemicals from latent sections of the chamber delivery paths. The chemical changeover may occur nearest to the chemical delivery source in the shortest period of time. Using timed switching of a series of valves for the fast evacuation paths, the pre-flow paths, and the chamber delivery paths, spaced along the chamber delivery paths from the chemical delivery source to the chamber, the new chemical mix and flow rate can be timed to be delivered at the chamber as close as possible to a requested time.

In one embodiment, feedback of the chemical delivery in the chamber delivery paths, the fast evacuation paths, and the pre-flow paths may be utilized. The chemical mix and flow rate can be measured in the various paths with pressure sensors, flow sensors, chemistry sensors, and/or other sensors monitoring conditions within the paths. The measured output of these sensors can be used to improve control of chemical delivery and to determine valve setting (i.e., open, closed, and proportional state) when changing the chemical mix and flow rate using any of the above methods. The transitional and steady state performance of the chemical mix and flow rate can be determined and adjusted using the sensors to control the timing used to change the operational setting or state of the valves.

In one embodiment, feedback of the chemical delivery into the chamber may be utilized. Pressure sensors, optical sensors, and other sensors providing feedback from the chamber can be used to determine the actual chemical mix and flow rate into the chamber. The measured output can be used to improve the control of chemical delivery and to determine valve settings when changing the chemical mix and flow rate into the chamber. The measured output can also be used to measure and determine the transitional and steady state performance of the chemical mix and flow rate.

In one embodiment, a predictive method of flow control may be used to minimize gas transition time. The method may include flowing the chemical mix at a flow rate other than the desired flow rate, and then converging to the desired flow rate to achieve equilibrium gas line pressure, and thus actual desired flow into the chamber in the shortest time possible.

In one embodiment, a predictive method of sequencing valves using a model of the flow system is provided. The method may include utilizing flow rate, volume of the gas delivery system, volume of the gas delivery lines, volume of the chamber showerhead, flow restriction of the gas delivery system, flow restriction of the chamber showerhead, equilibrium pressure at a given flow of the gas delivery system, valve actuation time, chamber pressure, foreline pressure, and/or gas species to sequence the valves of the systems to provide optimum gas delivery to the processing chamber for a particular etching/deposition process.

In one embodiment, a system may have one or more gas delivery systems, such that at least one gas delivery system is dedicated to a particular process condition. The dedicated gas delivery system, and thus the system, may require a reduced number of chemicals. The dedicated gas delivery system can be serviced by a small subset of flow controllers required for full processing of substrates, thereby saving significant cost and reducing the complexity of the system.

FIGS. 7A-C illustrate a gas transition process using the systems 100, 200, and 300 described herein. Delivery of a first gas 710 to a chamber 750 is stopped and delivery of a second gas 720 begins. As the second gas 720 flows into the line 760, a leading edge of the flow mixes with a residual portion of the first gas 710 in the line 760. The second gas 720 pushes the remaining first gas 710 through the line 760 and into the chamber 750. In one embodiment, a delay between providing a gas switch command and delivering the second gas 720 to the chamber 750 may be in a range of about 8 seconds to about 25 seconds. The gas transition timing can be improved by using the measurement methods and the predictive control methods described herein to alter the gas flow to rapidly provide optimum gas delivery to the chamber 750 for a particular etching/deposition process.

FIGS. 8A-C illustrate a gas transition process using the systems 100, 200, and 300 described herein. Delivery of a first gas 810 to a chamber 850 (via line 860) is stopped by closing a valve 865 and opening a valve 875, thereby exhausting the first gas 810 using a foreline 870 for example. At the same time as the first gas 810 is shut off, delivery of a second gas 820 through the line 860 begins. As the second gas 820 flows into the line 860, a leading edge of the flow mixes with and is diverted with a residual portion of the first gas 810 in the line 870. The second gas 820 pushes the remaining first gas 810 through the line 860 and into the foreline 870. The chamber 850 may continue to operate using another residual portion of the first gas 810 in the chamber. The valve 875 may then be actuated into a closed position and the valve 865 may be actuated into an open position to allow delivery of an uncontaminated flow of the second gas 820 to the chamber 850. The gas transition timing may occur within a time range of about 5 to about 10 seconds. Because the line 860 was evacuated during the dumping of the first gas 810, about 10 seconds to about 30 seconds may be required to provide a stable flow of the second gas 820 from the gas transition command.

FIGS. 9A-D illustrate a gas transition process using the systems 100, 200, and 300 described herein. The gas transition process may being as the process describe above with respect to FIGS. 8A-C regarding the delivery of a first gas 910 through a line 960 to a chamber 950. Valve 965 is in an open position and all other valves 967, 975, 985, and 987 are in a closed position. A line 980 is preloaded with a second gas 920 such that when the line 980 is connected to the chamber 950, a required amount of the second gas 920 is already in the line 980 to stabilize flow into the chamber 950. In one embodiment, a single transition gas may be used in the line 980. Valve 975 may then be actuated into an open position and the other valves may be actuated or remain in closed positions, to allow evacuation of any processing gas 930 (such as residual first gas 910) from the chamber 950 to an exhaust via a foreline 970, for example. Flow controllers may be used to stabilize flow through the foreline 970 before the gas transition. Valves 985 and 967 may then be actuated into open positions and the other valves may be actuated into or remain in closed positions. The second gas 920 may be delivered to the chamber 950 via the line 980, and the first gas 910 may be exhausted using the foreline 970. The gas transition may be dependent on valve timing. The gas transition has a relatively clean exponential rise and decay. The gas transition time to full stable flow of the second gas 920 may require about 2 seconds to about 5 seconds from the gas transition command. The exact time of transition may be calculated by using the direct measurement and/or predictive control methods described above from information provided by the one or more sensors 990.

FIG. 10 illustrates a gas delivery system 1000 that may be utilized with the embodiments described herein. The system 1000 may include a housing 1040, such as a grounded enclosure, coupled to the chamber 1050 for housing and locating one or more switching valves 1065, 1075, and 1085 as close as possible to the chamber and/or a showerhead coupled to the chamber 1050. The switching valves 1065, 1075, and 1085 may be housed within a grounded enclosure inside a gas source assembly. In one embodiment, the line 1080 may be dedicated to a particular gas transition process that requires only one gas.

Thus, gas delivery systems having fast evacuation paths advantageously enable processing gases supplying from the gas delivery systems into a processing system with stable gas flow and minimum fluctuation. The fast evacuation paths are utilized to provide an alternative manner to verify and/or calibrate gas flows from the gas delivery systems, thereby providing good control of the gas flow supplying to the processing chamber(s).

While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A method of etching a substrate in a chamber comprising: (A) depositing a protective layer on a first layer disposed on a substrate in an etch reactor; (B) etching the protective layer in the etch reactor, wherein a first bias power is applied during etching of the protective layer; (C) etching the first layer in the etch reactor, wherein a second bias power is applied during etching of the first layer; and repeating (A), (B), and (C) to form a profile in the substrate.
 2. The method of claim 1, wherein the first bias power is greater than the second bias power.
 3. The method of claim 1, wherein the first bias power includes a radio frequency range of about 2 MHz to about 13.56 MHz.
 4. The method of claim 1, wherein the second bias power includes a radio frequency range of about 100 kHz to about 400 kHz.
 5. The method of claim 1, wherein the first bias power and the second bias power include a power range of about 10 Watts to about 500 Watts.
 6. The method of claim 1, further comprising pulsing at least one of the first bias power and the second bias power within a duty cycle range of about 2% to about 40%.
 7. The method of claim 1, wherein the protective layer is a polymeric film.
 8. The method of claim 1, wherein the first layer includes a metal.
 9. The method of claim 1, wherein the first layer includes silicon.
 10. The method of claim 1, after (C), further comprising (D) depositing the protective layer on a second layer disposed between the first layer and the substrate, (E) etching the protective layer of material, and (F) etching the second layer to extend the profile.
 11. The method of claim 1, further comprising supplying a first gas into the etch reactor during (A) and supplying a second gas into the etch reactor during at least one of (B) and (C).
 12. The method of claim 1, wherein (A) is maintained for a time period of about 3 seconds, wherein (B) is maintained for a time period of about 3 seconds, and wherein (C) is maintained for a time period of about 5 seconds.
 13. A method of etching a substrate in a chamber comprising: depositing a polymeric film on the substrate during a deposition process; etching the polymeric film deposited on the substrate during a first etch process; and etching the substrate during a second etch process, thereby forming a profile in the substrate, wherein a first bias power is applied to the substrate during the first process, and wherein a second bias power is applied to the substrate during the second etch process.
 14. The method of claim 13, further comprising repeating the deposition process, the first etch process, and the second etch process to extend the profile in the substrate.
 15. The method of claim 13, wherein the substrate comprises a plurality of layers including at least one of silicon, oxide, and metal.
 16. The method of claim 13, wherein the first bias power is greater than the second bias power.
 17. The method of claim 13, further comprising pulsing at least one of the first bias power and the second bias power.
 18. The method of claim 13, further comprising supplying a first gas from a first gas panel into the chamber during the deposition process and supplying a second gas from a second gas panel into the chamber during the first and second etch processes.
 19. A gas delivery system comprising: a chamber for processing a substrate; a first gas panel in communication with the chamber by a first gas delivery line, wherein the first gas delivery line includes a first plurality of flow controllers; and a second gas panel in communication with the chamber by a second gas delivery line, wherein the second gas delivery line includes a second plurality of flow controllers, wherein the first and second plurality of flow controllers are selectively operable to direct gases from the first and second panels, respectively, to the chamber and to one or more exhausts that are in communication with the first and second gas delivery lines.
 20. The system of claim 19, further comprising a third gas panel in communication with the second gas delivery line, wherein the third gas panel is operable to delivery a gas to the chamber, the first gas delivery line, and the second gas delivery line to remove residual gases remaining in the system.
 21. A method of supplying gases to a chamber comprising: supplying a first gas to the chamber from a first gas panel through a first gas delivery line; directing a second gas to an exhaust from a second gas panel through a second gas delivery line while the first gas is supplied to the chamber; and directing the first gas to the exhaust and supplying the second gas to the chamber, wherein the first gas is removed from the chamber prior to introduction of the second gas into the chamber.
 22. The method of claim 21, further comprising a first flow controller in communication with the first gas delivery line for directing the first gas from the first gas panel to the chamber.
 23. The method of claim 22, further comprising actuating the first flow controller to direct the first gas from the first gas panel to the exhaust.
 24. The method of claim 21, further comprising a second flow controller in communication with the second gas delivery line for directing the second gas from the second gas panel to the exhaust.
 25. The method of claim 22, further comprising actuating the second flow controller to direct the second gas from the second gas panel to the chamber. 